Conventionally, for an insulated wire used in carrying out wiring of parts for an automobile and electric/electronic equipment, there is widespread use of an insulated wire in which a single layer of a vinyl chloride resin composition to which a halogenous flame retardant is added is arranged to cover a conductor.
However, there is a problem that the vinyl chloride resin composition includes halogen elements, so that it emits harmful halogenous gas into the atmosphere in case of car fire or at the time of combustion for disposing of electric/electronic equipment by incineration, causing environmental pollution.
Therefore, from the view point of reducing loads on the global environment, the vinyl chloride resin composition has been recently replaced with a so-called non-halogenous flame-retardant resin composition, which is prepared by adding a metallic hydrate such as magnesium hydroxide as a non-halogenous flame retardant to an olefin resin such as polyethylene.
However, the olefin resin is essentially combustible, and the non-halogenous flame retardant is inferior to a halogenous flame retardant in effect of flame retardancy. For these reasons, the non-halogenous flame-retardant resin composition requires a large amount of metallic hydrate to be added thereto in order to secure sufficient flame retardancy, thus bringing a disadvantage that mechanical properties represented by wear resistance remarkably degrade.
In order to overcome such a problem, Japanese Patent Gazette No. 3280099, for example, discloses an art to increase an affinity between a base resin and a metallic hydrate and improve mechanical properties such as wear resistance by using a plurality of olefin resins and rubbers as a base resin in which a specific functional group is further contained by a specific amount.